Summary: Three sets of experiments are proposed that address clinically relevant questions for cochlear implant patients, especially those who have and will receive the Hybrid (short-electrode) cochlear implant. The Hybrid is implanted only into the high-frequency region of the cochlea, but speech information provided through the implant is often from a lower frequency range not necessarily matched to the cochlear frequencies being stimulated. Preliminary data indicates that the pitch associated with stimulation to these basal electrodes can, for some patients, change dramatically over time to a much lower pitch sensation. The information obtained will increase understanding of how auditory perception can adjust to this spectrally shifted frequency-place information from cochlear implants, and how this relates to speech perception performance with the implant. Specifically, the project will: 1) measure pitch sensations in Hybrid cochlear implant users at various times from "hookup" up to 4 years of implant use, to determine if pitch sensations change over time; 2) test whether changing the speech processor frequency range causes pitch sensations to change, to compensate for the spectral shift of the speech; and 3) correlate speech perception performance with pitch sensations at various times, to determine how speech perception relates to pitch sensation. Relevance: The proposed research will study how much pitch perception changes over time, as a result of experience with hearing sounds through a cochlear implant, and whether perceived pitch can be a predictor of future speech understanding with the implant. These findings will have implications for how much the design of neural prostheses can be evaluated based on perceptual responses, which may be altered over time by experience. [unreadable] [unreadable] [unreadable] [unreadable]